Rotary operators or rotary selector switches are used to control electrical contact blocks or switches which are linearly operated. In the past, however, such operators have included cam members to translate the rotary motion of a handle to a linear motion to operate the contact blocks. In addition, separate members have been used around or above or behind the cam member to provide a detent arrangement to properly position the cam surface when the control knob is rotated. The use of such a detent arrangement requires multiple moving parts which complicate manufacture and assembly of the rotary operators. In the present invention, the cam surface is so designed that it operates directly against the operating extension or projection of the stroker or strokers of the contact block or blocks secured to the operator and provides the detent function.